1. Field of the Invention
This invention relates generally to a heat extracting device for use with fireplaces, stoves, furnaces, and the like, and particularly to a fireplace furnace which may be placed into an existing fireplace and function as a grate for fuel being burned in the fireplace as well as increase the heat transfer efficiency of the fireplace.
2. Description of the Prior Art
It is generally known to provide heat exchange devices to be used in conjunction with fireplaces, stoves, furnaces, and similar heating devices to increase the heat transfer efficiency of the heating device by facilitating heat conduction and heat convection mechanisms by which heat is transferred from the fireplace or other heating device into the room or other area or article being heated. The conduction of heat is the primary transfer mechanism from a fire to the surface of a fireplace furnace, although heat is also obtained by radiation. To a somewhat lesser degree, internal, or heat chamber, convection from a fireplace furnace is of prime importance, with radiation again providing some heat.
Considering the heating of the surface of a fireplace furnace, heat transfer by conduction is depended on three factors: (1) temperature within; (2) surface area of the furnace; and (3) the material from which the furnace is constructed. The temperature within the furnace is depended on the fuel being employed, and may be considered constant for any given system while the material selected for use in constructing the furnace is based on structural stresses resulting from the intense heat generated from fuel burned. Thus, surface area is the parameter most easily improved on in order to increase efficiency of a fireplace furnace.
It is generally known to provide fireplace furnaces in the form of grates constructed from at least one tubular member attached to other structural members, or other tubes, to form a grate-like framework. Examples of such fireplace grates may be found in U.S. Pat. Nos. 418,215, issued Dec. 31, 1889 to W. L. Nason, 2,702,030, issued Feb. 15, 1955 to O. B. Leibst, 3,001,521, issued Sept. 26, 1961 to A. L. Reilly, and 3,240,206, issued Mar. 15, 1966 to K. M. Schutt. U.S. Pat. No. 2,828,070, issued Mar. 25, 1958 to H. C. Snodgrass, discloses a hearth heater similar to the aforementioned prior art devices, but not specifically intended to function as a grate, while U.S. Pat. No. 2,375,318, issued May 8, 1945 to E. L. Mudgett discloses a draft device in the form of a box-like container having a planar top which forms a grate provided with a series of passageways receiving air from beneath the fireplace, with the device covering substantially the entire hearth of the fireplace. The latter mentioned device, however, must be used in conjunction with specially constructed fireplaces as must the fireplace and grate disclosed in U.S. Pat. No. 418,215, and the fireplace heater disclosed in U.S. Pat. No. 2,702,030.
Thus, it can be readily appreciated that fireplaces, although, used extensively are very inefficient. Accordingly, it has long been known to employ various kinds of fireplace furnaces in order to increase the efficiency of fireplaces, but the success of the prior art fireplace furnaces has generally not been sufficient to encourage their wide spread use.